Snap action switch



Dec. 24, 19467. w, NT'KEN 2,413,130

- SNAP ACTION swITcH Filed MaICh 1 1945 Weyl/ [za about midway between its ends,

Planea-peau, 194s UNITED STATES PATENT- oFFlcE l. Y sNAr 2115 :wrrcn Application Mai-eh 1, so,ass

The present invention relates to light pressure switches of the type wherein a spring in theform of a leaf, plate or blade snaps in one direction when a plunger or button is depressed and snaps back again upon the release ofthe plunger; and it has for its object to simplify and improvethe construction of such switches, increase the capacity thereof and, at the same time, bring about a very substantial reduction in size.

Au of such prior switches with which I am l familiar obtain very small gaps between contacts,

when opened, sometimes as little as one thirty second of an inch. Furthermore, the contacts themselves are small. These characteristics sharply limit the usefulness of the switches to situations in which only small currents need be handled; Vie'wed in one of its aspects, an object of the present invention is to overcome this weakv neSS.

'I'he aforesaid prior switches are also unsatisfactory because they are too bulky; and, in another oi' its aspects. my invention may be said to have for an object to reduce the size to such an extent that two of my switches will occupy n more space than is needed for one of the old style..

'Ehe various features o f novelty whereby my invention is characterized will hereinafter be pointed out with particularity in the claims; but for a full understanding of the invention and of its objects and advantages, reference may be had to the following detailed description taken in connection with the accompanying drawing, wherein:`

Figure 1 is a plan view of a switch embodying,

the said invention in a preferred form; Fig. 2 is a section taken online 2--2 of Fig.' 1; Figs. 3 and 4 are sections taken, respectively, on lines 3-3 and 4 4 of Fig. 2: Fig. 2A is a fragmentary elevational view illustrating an alternatemethod of supporting the movable switch member; Fig. 5 is a view, similar to Fig. 1, with the casing cover removed; Fig. 6 is a view similar to Fig. 2, vbut with'a part of the base in section, illustrating a second vform of movable switch element; Fig. 7 is a side view, on a smaller scale, showing a'switch and an operating means therefor; and Fig. 8 is ariend elevationof the devices appearing in Fig. 7.

Referring to Figs. 1 to 5, I0 is a movable switch member which constitutes the most important feature of the present invention. It consists simply of a long, narrow leaf spring", preferably made from beryllium copper. It is provided,

with thick diSIBS 2 Il, one on each face, of pure silver. The spring overlies and extends lengthwise of the base member I2. of a long. narrow casing or housing of insulating material. Cooperating with the base is a cover I3 in the form of a deep, inverted pan. One end of the spring overlies ashort post or upward projection Il on end of the base.' within theV interior of .the casing, and is rigidly yt. Secured and held by a screw `I5 that passes through the spring and into a binding post I s embedded in the part Il. Aat terminal Il extends from the binding post out through the corresponding end of the casing. In the opposite end .of the casing is a somewhat higher post or projection I8, rising from the base, A pin I9, passing through the long side walls of the cover and the post 18, serves to fasten base and cover together. In the side of the post I8 facing the post I4 is a block 20 of metal that contains a V-shaped notch or groove 2| extending across the width of the same. The free end of the spring is engaged in this notchor groove to provide a rocking connection between this post and the spring.- The parts are so shaped and proportioned that the spring is normally bowed upwardly suillciently to cause the upper contact disc to be pressed forcibly against the overlying cover.

forcibly against the base. The cover and the base f l v lare respectively provided with stationary contact pieces 22 and 23, one to be engaged by the upper contact disc onv the spring in the normal positions of the parts, while the vother is engaged by the lower contact vdisc when the direction pf curvature of the spring is reversed. Terminal elements 2l and 25, similar to terminal I1, but longer, extend from the stationary contacts, 22 and 23, respectively, through the end of the casing opposite that at which the terminal l 'I is located. Since the terminals are arranged one above theother the width of the device need not be increased to provide adequate spacing between them.

Since in switches of the type under consideration the movable member must remain in or move into what may be termed its normal working position, except while held in its other working position by an external force, means must be provided in the instant case to bring thisabout, insure properpressure between cooperating contacts in each of the two working positions, and achieve a very rapid or snap movement after the spring has been initially flexed and also after it lhas been released. I have found thatfthis may be accomplished by providing the spring with a small downward bulge 28 near its ilxed end and a similar, upward bulge 21 near the other end. These bulges may be made in various ways. Thus, in the arrangement shown, little hemispherical cups or protrusions, smaller in diameter than the width of the spring, are fashioned by deforming or extruding the metal of the spring to protrude in relatively opposite directions at the proper points. The spring is moved out of its normal position, that indicated in full lines in.

Fig. 2, through pressure on a little plunger 28 passing straight down through the top wall of the cover of the casing and provided. with an insulated head 29 that engages the top side of the spring adjacent to the bulge 26. Thev head is preferably cone-shaped to enable it to exert a wiping action against the slightly arcuate shoulder 3l! formed in the spring at protrusion 26, while the spring is bowed upwardly. Upon depressing the plunger, the spring is initially iiexed and then rapidly snaps down into the broken line position where it remains until the plunger is released. As soon as the plunger is released the spring quickly snaps back into its normal position.

39, to avoid making the overall length of the device too great. 'I'he lever overlies the plunger 28, so that when it is swung down it depres'ss the plungerand throws the switch from the full line position to the broken line position. The lever may be actuated by a cam 40 on a rotating shaft-4I; the cam being aboveand resting on the turned back section of the lever.

While I have illustrated and described with particularity only the preferred form of my invention, including a slight modiiication in the While I prefer to leave the left hand end of the spring free to rock instead of bending, when the spring snapsdown, both ends may be held fast. Thus in Fig. 2A, instead of the high post rising from the left hand end of the base in the other form, there is a low post, ida; the spring overlying this post as well as post ifi, and being secured thereto by a screw los.

It will be seen that there is a large gap at the open side of the switch in whichever position it may be. Thus, in a device wherein the casing has an outside length of a little less than two inches and a width of three eighths of an inch, the gap is at least five thirty-seconds of an inch. This, coupled with the fact that the actual contacts may be quite large and heavy, makes it possible to handle much heavier currents than is true with the old switches. Also, because all of the contacts have their centers in the same longitudinal vertical plane, instead of in a transverse plane, the

spring member of the switch, I do not desire to be limited to the exact structural details thus illustrated and described; but intend to cover all forms and arrangements and means for supporting the ends of said spring member which come within the deiinitions of my invention constituting the appended claims.

I claim:

l. In a switch, a Single elongated narrow leaf spring rigidly held at one end, a stationary support for the other end of the spring at such a distance from the ixed end that the spring normally bows upwardly', said support leaving the spring free to rock up and down on the support about the adjacent end edge of the spring, a stationary contact positioned above the spring at about the middle and normally pressing against and stressing it, the spring having near each end thereof an integral protrusion of transverse width less than the width of the spring, the protrusion near the fixed end of the spring being downward and the other being upswitch need be only one half as wide as one in which the stationary contacts must be spaced apart across the width of the device for cooperation with one end of a spring member. It therefore follows that two of my switches may be placed side by side in the same space as is required for one of the old switches; and, furthermore, that one of my switches will satisfactorily carry fifteen amperes as against ten amperes for the latter.

In the device shown in Fig. 6 the parts are the same as those in Fig. 2, except that the bulges 3i and 32 in the spring 33 result from bending the spring along lines extending transversely thereof to form U-shaped loops.

When a number of the switch devices are to be grouped together, they may be placed side by side and secured by fastenings passing through holes 34 in the base member; these holes also being adapted to receive fastenings or supporting means in mounting individual devices.

In Figs. '7 and 8 I have illustrated a suitable operating means for the switch. This consists of a spring lever 35 having at one end a jaw 36 which embraces an ear 3l at the end of the cover at which the plunger is located. A pin 3d joins the jaw to the ear and forms a spindle about which the lever may rock. The free end of the lever may be bent back, hair pin fashion, as at ward, a plunger above the spring in position adapted to exert pressure thereon beside the downward protrusion to slightly iiex the spring and thereby cause it to quickly reverse its curvature, and a second stationary contact below and normally remote from the middle of the spring adapted to be engaged by the spring when the plunger is depressed and the curvature of the spring is reversed.

2. In a switch, a long narrow base having upward projections near its ends, a long narrow leaf spring overlying said base and fixed at one end to the top of one of said projections, the second projection having in the side' facing the iirst projection a transverse notch positioned a substantial distance above the base, the free end of the spring being seated in said notch to hold the spring in an upwardly bowed condition and enable it to rock about the end edge that is seated in the notch, a cover forming with the base a casing for the spring, a stationary contact mounted on the inner side oi the cover above the middle of the spring and normally pressing against and stressing the spring, the spring having near its ends hemispheric protrusions extending at least part way across the width thereof, the protrusion near the fixed end of the spring being downward and the other protrusion being upward, and a plunger reciprocable through the cover disposed above the spring and positioned to exert a downward pressure on the spring near the downward protrusion when the plunger is depressed, thereby causing the spring first to flex and then quickly reverse its curvature, together with a second stationary contact on top of the base below the middle of the spring adapted for engagement by the spring when the plunger is depressed and the curvature of the spring reversed.

3. A. movable member for a snap switch consisting of a single elongated narrow` leaf spring normallyl disposed in upwardly bowed position and having near each end a single protrusion one of which is disposed upward and the other downward, and contact pieces iixed to opposite faces of the spring about midway between its ends.

4. In a switch, a casing including a comparatively narrow but elongated base and a cover therefor, a movable switch member within the casing extending longitudinally thereof and comprising an elongated narrow leaf spring, stationarymeans supporting the ends of the spring on said base and holding the spring in an upwardly bowed condition, the spring having near one end thereof a single upwardly disposed protrusion and near the other end thereof a single downwardly disposed protrusion, stationary contacts in thef casing, an upper one of said contacts being secured to the underside of said cover and a lower one of said contacts being secured to said base and both of said contacts being vertically aligned at about the middle of the spring, said spring carrying contact means at about its middle portion so arranged that said contact means normally presses against the upper one of said stationary contacts, and an actuator adapted to be pressed downwardly to engage the spring near the downwardly disposed protrusion whereby the spring is initially flexed and caused to quickly snap away from the up'per one of said stationary contacts and thereby reverse its curvature so as to engage the lower one of said stationary contacts when the actuator is vmoved down, said spring being adapted to quickly snap upwardly into normal engagement with the upper one of said stationary contacts when the actuator is released.

5. In a switch as set forth in claim 4, wherein said protrusions are rigid cup-shaped extrusions of the material of the spring and of transverse nally of the cover and base.

7. A switch as set forth in claim 4 wherein there are three laterally extending terminals one of which is secured to the base and connected to a fixed end of the spring, another of said terminals being secured to the stationary contact on the base and the other one of said terminals being secured to the stationary contact on the cover, said terminals extending outwardly of the casing and beyond the outer sides of the cover therefor.

8. A movable member for a snap switch consisting of asingle elongated relatively narrow leaf spring normally disposed in bowed position having near each end thereof a single deformation in the body of the spring, said deformations constituting transverse stiffeners in the spring body in the form of protrusions projecting from the spring body in relatively opposite directions,

and at least one circuit making and breaking contact piece carried by the spring at about midway its ends.

\ WILLIAM J. AITKEN. 

